var enabledStyleOpacity;
var enabledStyleMozOpacity;
var enabledStyleFilter;

function disableButton(button) {
//            alert('disableButton(' + button + ')');
    //        alert('disableButton(): button.tagName = ' +button.tagName);
    //         alert("button.style.opacity: " +button.style.opacity + "\n button.style.MozOpacity: "+button.style.MozOpacity +"\n button.style.filter: "+button.style.filter);
    if (!button.disabled) {
        var style = button.style;
        //        alert('disableButton(): style = ' +style);
        enabledStyleOpacity = style.opacity;
        enabledStyleMozOpacity = style.MozOpacity;
        enabledStyleFilter = style.filter;
        button.disabled = true;
        style.opacity = 0.25;
        style.MozOpacity = 0.25;
        style.filter = "Alpha(opacity=25), gray()";
    }
}

function enableButton(button) {
//            alert('enableButton');
    if (button.disabled) {
        button.disabled = false;
        button.style.opacity = enabledStyleOpacity;
        button.style.MozOpacity = enabledStyleMozOpacity;
        button.style.filter = enabledStyleFilter;
    }
}

// todo вынести все методы getFalseReturn() в один файл JS
function getFalseReturn(){
    if (navigator.appVersion.match("IE")){
        event.returnValue = false;
    }
    return false;
}

/*
 * @return false - if there is no radiobuttons with specified name
 */
function uncheckRadioButtonsByName(radioButtonName) {
//    alert('uncheckRadioButtonsByName('+radioButtonName+')');
    var radios = document.getElementsByName(radioButtonName);
    if(radios != null) {
        for(var i =0; i<radios.length; i++) {
            radios[i].checked = false;
        }
        return true;
    } else if(radios == null) {
        return getFalseReturn();
    }
}

/*
 * @param radioButton - Element. radiobutton to check
 */
function checkRadioButton(radioButton) {
//    alert('checkRadioButton('+radioButton+')');
    radioButton.checked = true;
}